Apparatus for beating and disintegrating fibrous materials in liquid suspension



Mm 3, W7 N. G. H. NILSSON 3,295,769

APPARATUS FOR BEATING AND DISINTEGRATING FIBROUS MATERIALS IN LIQUID SUSPENSION Filed Dec. 2, 1964 2 Sheets-$heet 1 Jam 3, 1? N. G. H. NHLSSON 9 9 APPARATUS FOR HEATING AND DISINTEGRATING FIBROUS MATERIALS IN LIQUID SUSPENSION Filed Dec. 2, 1964 2 Sheets-Sheet 2 m waj m 15 15 14 15 55' 51 34 m United States Patent 3,295,769 APE'ARATUS FQR BEATING AND DISHNTEGRAT- FEBRQUS MATERIALS EN LIQUID SUSPEN- N Nils Gunnar Holger Nilsson, Segersminnevagen 7, Huddinge, Sweden Filed Dec. 2, M64, Ser. No. 415,542 Claims priority, application Sweden, Dec. 17, 1963, 14,641/63 9 Claims. ((Zl. 241-45) This invention relates to so-called pulpers, boaters or similar apparatuses for disintegrating fibrous materials in liquid suspension, such as waste paper, previously dried paper pulp or similar paper stock materials in water in manufacturing paper, pasteboard or the like, and the main object of the invention is to provide an improved apparatus of the kind mentioned in which already disintegrated m-aterial, i.e. the mutually separated or loosened fibres in the suspension treated, may be continuously strained off through a screening device during the heating process in a most efiicient manner and under most advantageous conditions from case to case so that the risk of clogging the screening device and, hence, disturbing the proper operation of the apparatus is highly reduced.

More particularly the invention is concerned with an apparatus for beating and disintegrating fibrous materials in liquid suspension of the type which comprises a container for receiving the material to be treated as well as the suspending liquid for the same, said container having an opening in its wall, a rotary impeller mounte at the end of a driving shaft in said opening of the container, said impeller having substantially radially extending fins projecting into said container to cause, when said impeller rotates at a high speed, an intense circulation of the liquid in said container and also a mechanical beating and, hence, disintegration of the liquid suspended material coming into contact with said impeller fins, and. an annular screening device surrounding said rotary impeller in said opening of the container, said screening device forming part of an outlet duct for said container.

Apparatuses of that particular kind are previously known in two different forms. In the first form the an paratus has a stationary screening device which is secured to the container, and in the second form the apparatus has a screening device which is secured to the impeller to continuously rotate with the same speed and in the same direction as the latter. In the first case there is an accentuated tendency of the fibre suspension to rapidly clog the screen openings so that very little of the disintegrated fibrous material will, in fact, be permitted to depart from the container and even the liquid may have difficulties in escaping. in the second case on the other hand, the material circulated past the screening surface will become highly accelerated in radial direction also by the screening surface itself, since the latter is rotating at the same high speed as the impeller, and, although this will certainly reduce clogging of the screen openings, the separated fibres which are supposed to escape through the screen openings will instead show a tendency to jump over said openings and thus remain in the container, while at the same time the incompletely disintegrated material will be subjected to very little rubbing or knead ing when passing over the screening surface. In both cases there is a considerable risk of unintentional severing and shortening of the fibres by too much beating and in addition thereto it is, of course, highly uneconomical to work the material more than absolutely necessary.

All these disadvantages of the previously known apparatuses may be avoided in a very favourable manner by the improved apparatus according to this invention,

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which is mainly characterized by the fact that the screening device is separate from said rotary impeller as well as from said container and mounted on a tubular shaft surrounding said impeller driving shaft in a manner to be independently rotated relatively to said impeller. With such an improved arrangement the impeller may rotate at a high speed, while the screening device may be rotated at a lower speed which is considerably more adapted for obtaining a departure of the loose or freed fibres from the container, and the screening device may also rotate in opposite direction relatively to the impeller to promote the escapement of the freed fibres and/ or the rubbing and kneading action of the screening surface on the material remaining in the container. Additionally, rotating the screening device in a direction opposite to the impeller can be utilized to improve the flowing conditions of the material within the container by counteracting the cyclonic or whirling motion of the liquid and suspended material in the container produced by the impeller which motion, as well known, may rather considerably reduce the beating action of the impeller.

As will be readily understood, it will also be possible according to this invention to change the direction of rotation of the screening device at certain intervals whereby the possibilities to prevent clogging of the screening device may be still further increased. Furthermore, it will be possible to make the independently rotatable screening device in such a manner that it will develop a more accentuated screening or straining performance, when rotating in the one direction, and a more effective kneading and fibre loosening performance, when rotating in the opposite direction.

For further elucidation of the invention reference will now be had to the accompanying drawings, wherein:

FIG. 1 is a sectional elevation of a first apparatus embodying the invention,

FIG. 2 is a top plane view of the apparatus of FIG. 1,

3 is a partial sectional elevation of a second apparatus embodying the invention,

FIG. 4 is a horizontal section taken along the line lV-IV in FIG. 3 and illustrating an independently rotatable screening device in which different sectors show different forms of blades,

5 is a radial section of a screening device of the type illustrated in FIG. 3 but showing a modified form of blade,

FIG. 6 is a cross section taken along the line VI-VI in P16. 5,

FIG. 7 is a radial section similar to FIG. 5 but showing a further modified form of blade, and

FIG. 8 is a cross section taken along the line VIII- Vlll in FIG. 7.

The apparatus illustrated in FIGS. 1 and 2 comprises a container iii which is open at its top and supported by suitable legs 11. To the lower side of the container bottom there is attached a housing structure 12 forming a downward extension of the container and defining a circular central opening 13 in the bottom wall of the container. Centrally located in said opening 13 there is a disk-like impeller 14 having on its top a number of radially or at least substantially radially extending fins l5 projecting into the container 1h. The impeller 14 is carried by a central driving shaft 16 having a driving pulley 17 or cog wheel secured to its lower end. Surrounding the impeller 14 in the opening 13 there is an annular screening device which is generally designated by numeral 18 andwhich comprises a slightly conical and perforated screen plate 19 mounted on top of an annular pump rotor 2i which in its turn is carried by a tubular shaft 21 surrounding the impeller driving shaft 16 and having a driving pulley 22 or cog wheel secured to its lower end. The screen plate 19 as well as the pump rotor 20 are fully separate from the impeller 14 as well as from the container so that they can rotate independently of said impeller 14. The pump rotor comprises substantially radially extending blades 20' located under the screen plate 19 so that the screening device 18 will act as a centrifugal pump within the housing 12, the interior of which, preferably but not necessarily, is spirally shaped as indicated by dotted lines at 12 in FIG. 2 and has a substantially tangential outlet 23 for the accepted fiber suspension passing through the screen plate 19.

The impeller driving shaft 16 is journalled in upper and lower bearings 24 and 25, respectively, of which the upper one, 24, is seated within an upper, widened end portion of the tubular shaft 21 while the lower one, 25, is mounted in a yoke 26 secured to the lower end of the housing 12 and at least partially exposing the pulley or cog wheel 22 of the tubular shaft 21. Suitable sealing rings 27 are interposed between the upper end of the impeller driving shaft 16 and the surrounding tubular shaft 21 to prevent liquid leakage to the bearing 24. The tubular shaft 21 is in its turn journalled in vertically spaced bearings 28 and 29, respectively, mounted in the lower, sleeve-like portion of the housing 12. A suitable sealing ring 30 is interposed between the upper portion of the tubular shaft 21 and the housing 12 to prevent liquid leakage to the bearings 28 and 29.

It should be readily understood that both the pulley 17 and the pulley 22 or their equivalents are intended to be driven through suitable transmissions (not shown). The pulley 17 and hence the impeller 14 should be imparted a high rotational speed and there is commonly no need for changing this speed or reversing the direction of rotation of the impeller 14 during the normal Work of the apparatus. The pulley 22, and hence the independently rotatable screening device or screen and pump rotor assembly 18, on the other hand, is intended to be driven at a variable speed and, preferably, there should also be provided means for reversing the direction of rotation thereof. Consequently the pulley 22 may either be driven from a suitable driving motor separate from the motor driving the pulley 17 or from the same driving motor as the pulley 17 through a suitable own transmission or gearing including a step gear box, a reversing gear, or, most suitably, a continuously variable and reversible speed gear. Since the driving of the two pulleys 17 and 22, respectively, may be accomplished in many different ways which, no doubt, will be obvious to the man skilled in the mechanical art, and since the invention is not in any way restricted to any specific driving arrangement, such transmissions and gears have not been illustrated.

Evidently the pumping action of the screening device 13 will vary if not entirely cease when the direction of rotation of the screen and pump rotor assembly is reversed in the apparatus shown in FIGS. 1 and 2. Furthermore, reversing the direction of rotation of the screening device 18 in relation to the direction of rotation of the impeller 14 will counteract the cyclonic or whirling motion of the suspension in the container 10 about a vertical axis forming an imaginary extension of the impeller shaft 16 so that more advantageous, substantially radial and vertical circulation of the contents of the container 10 will be achieved.

The apparatus illustrated in FIGS. 3 and 4 is substantially similar to the one described in connection with FIGS. 1 and 2 and all parts, which are similar in both, have been designated by the same numerals. The only difference is that the independently rotatable screening device 18 has been replaced by a modified type of screen and rotor assembly, generally designated by numeral 31, which, however, is still independently rotatably mounted on the tubular shaft 21 and driven by its own separate pulley or cog wheel 22. The screen and rotor assembly 31 comprises a lower, annular disk portion 32 carrying on its upper side an annular series of substantially radially extending blades 33 which are all of the same size and of a substantially Wedge-shaped configuration. All the blades 33 are turning an edge upwards and towards the interior of the container and said blade edges define between them radially extending screening gaps, through which the accepted suspension may leave the container. In order to mutually support the blades 33 and hold them together, there is provided a rim-like ring 34 to which the upper, outer corner of each blade 33 is secured.

In FIG. 3 the blades 33 have substantially straight upper edges forming substantially a direct continuation of the surrounding container bottom portion over which the radial fins 15 of the impeller 14 projects. As may be seen from FIGS. 5 and 6, however, there may also be used blades 35 having a saw-toothed upper edge 36, which will of course exert a more accentuated rubbing and kneading action on the suspended material repeatingly passing over the top surface of the independently rotatable screening device. As will be seen from FIG. 6 the blades 35 may also be slightly slanted, which will result in a slightly more vigorous pumping action of the blades 35 when the screen and pump rotor assembly rotates in the one direction at a certain speed than when the assembly is rotating in the opposite direction at the same speed.

In a further modified form illustrated in FIGS. 7 and 8 the blades 37 may have a toothed or crenela-ted upper edge, the tooth-like projection 38 of which are bent out of the plane of the related blade 37, either all towards the same side or, as shown in FIGS. 7 and 8, alternately in opposite direction to partially cover the gaps on either side of each blade 37. In the latter case the toothed or crenelated upper edges of adjacent blades will cooperate to form radial series of staggered screening openings in the top surface of the screen and rotor assembly. Also with the arrangement illustrated in FIGS. 7 and 8 an improved rubbing and kneading action on the material passing over the screening surface will be achieved. The different types of blades now described have been shown as viewed from above in difierent sectors of the annular screening device 31 of FIG. 4, it beeing understood, however, that in practice one single type of blade should be selected and used throughout in such device.

Although the invention has now been described with reference to certain preferred embodiments thereof, it must not be considered restricted to the details of said illustrated embodiments. Thus it is not at all necessary to locate the impeller and the independently rotatable screening device surrounding the same centrally in the bottom wall portion of the container id but in certain cases they may as well be mounted in an opening provided in the side wall of the container or eccentrically in the bottom Wall of the container. Also several other modifications may be made without departing from the scope of the appended claims.

I claim:

1. An apparatus for beating and disintegrating fibrous materials in liquid suspension and comprising a container for receiving the material to be treated as well as the suspending liquid for the same, said container having an opening in its wall, a rotary impeller mounted at the end of a driving shaft in said opening of the container, said impeller having substantially radially extending fins projecting into said container to cause, when said impeller rotates at a high speed, an intense circulation of the liquid in said container and also a mechanical beating and, hence, disintegration of the liquid suspended material coming into contact with said impeller fins, and an annular screening device surrounding said rotary impeller in said opening of the container, said screening device forming part of an outlet duct for said container, characterized in that said screening device is separate from said rotary impeller as well as from said container and mounted on a tubular shaft surrounding said impeller driving shaft in a manner to be independently rotated relatively to said impeller.

2. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 1, wherein said independently rotatable, annular screening device comprises a rotor assembly including blades operative to pump the accepted suspension out through the outlet duct of said container at the rotation of said screening device.

3. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 2, wherein said pump rotor assembly of the independently rotatable, annular screening device includes blades arranged to impart to the accepted suspension a more vigorous motion, when said screening device is rotating in the one direc tion at a certain speed than when the screening device is rotating in the opposite direction at the same speed.

4. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 1, wherein said independently rotatable, annular screening device comprises a perforated plate mounted on top of a centrifugal pump rotor carried by said tubular shaft and also separate from said rotary impeller, said centrifugal pump rotor operating in a spirally shaped chamber forming part of the outlet duct of said container.

5. An apparatus for beating and disintegrating fibrous materials in liquid suspension and of the kind comprising a container for receiving the material to be treated as well as the suspending liquid for the same, said container having an opening in its wall, a rotary impeller mounted at the end of a driving shaft in said opening of the container, said impeller having substantially radially extending fins projecting into said container to cause, When said impeller rotates at a high speed, an intense circulation of the liquid in said container and also a imechancal beating and, hence, disintegration of the liquid suspended material coming into contact with said impeller fins, and an annular screening device surrounding said rotary impeller in said opening of the contaner, said screening device forming part of an outlet duct for said container; Wherein said screening device is separate from said rotary impeller as well as from said container and mounted on a tubular shaft surrounding said impeller driving shaft in a manner to be independently rotated relatively, to said im peller, and wherein said screening device comprises an annular series of substantially radially extending blades each turning an edge towards the interior of said container, said blade edges defining between them screening gaps through which the accepted suspension may-leave the container.

6. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 5, wherein said substantially radially extending blades are slanted.

7. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 5, wherein said edges of the blades facing the interior of the contain-er are toothed.

8. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 5, wherein said edges of the blades facing the interior of the container are provded with tooth-lke projections bent out of the plane of the related blade.

9. An apparatus for beating and disintegrating fibrous materials in liquid suspension according to claim 8, wherein said tooth-like projections of each blade are alternately bent in opposite direct-ions out of the plane of the related blade to partially cover the gaps on either side thereof.

No references cited.

WILLIAM W. DYER, JR., Primary Examiner. G. A. DOST, Assistant Examiner. 

1. AN APPARATUS FOR BEATING AND DISINTEGRATING FIBROUS MATERIALS IN LIQUID SUSPENSION AND COMPRISING A CONTAINER FOR RECEIVING THE MATERIAL TO BE TREATED AS WELL AS THE SUSPENDING LIQUID FOR THE SAME, SAID CONTAINER HAVING AN OPENING IN ITS WALL, A ROTARY IMPELLER MOUNTED AT THE END OF A DRIVING SHAFT IN SAID OPENING OF THE CONTAINER, SAID IMPELLER HAVING SUBSTANTIALLY RADIALLY EXTENDING FINS PROJECTING INTO SAID CONTAINER TO CAUSE, WHEN SAID IMPELLER ROTATES AT A HIGH SPEED, AN INTENSE CIRCULATION OF THE LIQUID IN SAID CONTAINER AND ALSO A MECHANICAL BEATING AND, HENCE, DISINTEGRATION OF THE LIQUID SUSPENDED MATERIAL COMING INTO CONTACT WITH SAID IMPELLER FINS, AND AN ANNULAR SCREENING DEVICE SURROUNDING SAID ROTARY IMPELLER IN SAID OPENING OF THE CONTAINER, SAID SCREENING DEVICE FORMING PART OF AN OUTLET DUCT FOR SAID CONTAINER, CHARACTERIZED IN THAT SAID SCREENING DEVICE IS SEPARATE FROM SAID ROTARY IMPELLER AS WELL AS FROM SAID CONTAINER AND MOUNTED ON A TUBULAR SHAFT SURROUNDING SAID IMPELLER DRIVING SHFT IN A MANNER TO BE INDEPENDENTLY ROTATED RELATIVELY TO SAID IMPELLER. 